Hi everyone

1.4 Mpi Fabia (2000 reg)

Just driven to work this morning, Dewsbury to Leeds via Wakefied (to drop of my wife at work). Took about 40 minutes for approx. 15 mile journey, with a clear run up a stretch of the M1 and the rest of it in 30mph zones.

The temperature guage did not lift off the bottom at all. But could this be due to the fact that it was cold. Didn't set off until 9am but I still had frost on the windows.

I've been getting bad fuel economy for quite some time (about 25 mpg) and I know a faulty temp sensor can cause that. But up until very recently the temperature gauge has always gone to the half way mark and no higher (indicating, or so I thought, that it was running fine).

Any suggestions would be welcome. I guess I could change the temp sensor anyway. Are they quite cheap to buy? The only thing with that is that it was only changed this last April.

Thanks

Ian

Edited 15 December, 200817 yr by itgoodson
Forgot to state car model

Coolant temp sensor, almost certainly!

Did a replacement guide, here, although you may want to replace the entire thermostat body (comes as a pack with a new sensor) if it's not been done before. I did mean to do a guide, but couldn't better the one in Haynes, and was a bit worried about copyright! Easy enough job as long as you take the time to drain the coolant.

I can say it's the sensor with reasonable certainty because of your duff fuel economy, and because it usually first presents as an 'all or nothing' intermittent fault on the gauge. If it was the 'stat, then you'd get a 'wobbly' reading on the gauge all the time, and potentially no heat in the cabin.

It's definitely worth getting it done. Sensor alone shouldn't be more than GBP30 from a dealer (GBP20??? from elsewhere???), and is a fifteen-minute job (most of that's getting the engine cover off on the MPi! )

If you go for the 'stat body as well (recommended as they last no more than six or seven years IME), get the parts off the internet, and give yourself a couple of hours - most of which will be the coolant draining, and then filling it up again and topping it off. As I say, this job's all in the Haynes, and despite some of the criticism of the book as a whole, this particular job is pretty well covered.

HTH

This is excellent - thanks ever so much. Yes, there was heat in the cabin, nice and warm once it all got going. I'll check the temperature gauge on the way home too.

Now I need to do this all before I drive the length of England (more or less) on Friday and I have an exceptionally busy week ahead! Any recommendations where I can get the thermostat body off the internet at a reasonable price and quickly too?

I don't have access to the Haynes manual either! I might just give my local library a ring to see if they have it.

I've often used Jorily, although most places that stock VAG parts should heve them. I don't know the part number for the sensor / 'stat body pack, I'm afraid, but if time's of the essence you might have to go somewhere and buy over the counter rather than risking mail order at this time of year. Under the circumstances, I'd recommending getting the pack, but just fitting the new sensor. Then you can replace the 'stat body when you have a bit more time and put the 'new' sensor back into the new 'stat body. It'll mean you can do the work without a copy of Haynes for now, as well!

Thanks again Ap0gee!

Seeing that the temp sensor was changed back in April this year, could it be that the stat body could be what's causing the fault rather than the sensor itself? In other words, when the stat body goes (you said they last six or seven years) can that cause the fuel efficiency problem? Hope that question makes some sense! Cheers

P.S. I've looked at Jorily

I take it this is the sensor I need Skoda Fabia/Octavia Engine Temperature Sensor - £17.63 : Skoda Parts, Jorily, The Skoda Parts Shop - Probably the UKs largest independent skoda parts supplier

Is this the whole stat pack you're talking about Skoda Fabia 1.0/1.4 Thermostat/Temperature Sensor Complete - £26.45 : Skoda Parts, Jorily, The Skoda Parts Shop - Probably the UKs largest independent skoda parts supplier

Thanks!

Ian

Edited 15 December, 200817 yr by itgoodson
add more info

As I think about it, I reckon I will have a go at changing the whole thermostat pack (as long as I have got the right part in mind - see above!)

Will changing it be as straight forward as looking at the existing one, draining the coolant off, taking the old one out and fitting the new one in, then topping the coolant up again?

If so I may have a go without the Haynes!!! How do I drain the coolant off? What will happen if I just take the part off and the coolant drains out as I do so? Is that an ok way of doing it? (don't mock - I'm a novice, although I did change the steering angle sensor all by myself in the summer!)

Regards

Ian

Ap0gee, if you're still there...

I've telephoned a few parts places, inc a Skoda dealer and independant stores. Skoda does the whole kit for £37 + VAT. But I can just but the thermostat kit on it's own for £14.99 from an independant store.

Seeing that the temperature sensor was changed in April as it is, do you think I should change just the thermostat for now? Or am I best off changing the whole kit really? Can a faulty thermostat (rather than a faulty temp switch) cause the sympoms I have (i.e. poor fuel economy and no movement of temperature gauge on dash)

I guess my question is how do I know whether the thermostat isn't working properly? I am quite sure that when I turn the temperature up and down in the cabin it all responds ok. Does this indicate that the thermostat is working ok and that the problem is really with the temp sender/sensor?

Thanks

Ian

Edited 15 December, 200817 yr by itgoodson
add info

Back again!

As I say, a faulty 'stat will cause the temperature to rise a bit, but it'll never get to full temperature, as the circuit to the radiator is always open. If the sensor is relatively new, it might be worth trying a spot of WD40 on the contacts before replacing it, as it could just be a dodgy connection in this cold, damp weather... I don't think a faulty thermostat would cause no temperature rise on the gauge one day, and a 'normal' temperature rise the next - as I described earlier, you're more likely to see it wobble around the 70deg mark rather than sitting at 50 or rising to 90.

You're right about identifying the parts in post #5 - the thing is that the plastic thermostat body degrades over time and becomes brittle. Eventually, one or other of the two lugs that the thermostat clips into break off, and the thermostat fails. Therefore, buying the thermostat on its own won't be any good. In fact, you could probably re-use the thermostat plunger in theory, but you can't buy the body without the thermostat, so it's not worth bothering.

As I say, check the connections on the sensor, but if it comes to it, you're best not trying to replace it without draining the system - this is what I tried, and what made me say I can't beat the Haynes method. In summary, you drain the coolant using the tap on the bottom corner of the radiator into a washing-up bowl or similar, then disconnect the hoses using a set of mole grips (or large pliers if you have strong hands) and the cable to the sensor. Undo the two nuts that hold the 'stat body onto the top corner of the engine (quite stiff IME - try some WD40 if you struggle, perhaps) and make a straight swap. Put everything back together in reverse order, and pour the coolant back into expansion tank, leaving time for it to run into the various nooks and crannies. Then start the car up, put the temperature control in the cabing to 'hot' and leave it running until it gets to temperature. Then switch off, leave it to cool, and top up the coolant in the expansion tank (taking care of any steam if you can't leave it to cool for any reason). If you spill any coolant, the red / purple Halfords coolant meets G12 spec (although it describes is as 'TL44D' or something), whereas the stuff you get from a dealer is the more advanced G12+. The two are readily mixable AFAIK, and if you're mixing your own, don't worry about an exact 50:50 mix - it works up to 60:40 either way, AIUI.

Hope you get it sorted!

This is really good advice - really appreciate it.

I spoke to my local Skoda dealer a few minutes ago. The guy said quite authoritatively that the thermostat has collapsed and that I should replace the whole unit. So I've ordered the kit and it will be there in the morning.

My plan is to watch the temp gauge on the way home in a couple of hours and as you said check the connections and apply some WD40 and see what that does. Like you say ap0gee, I don't understand why the temp gauge has been working some times and not at other times. Let's see how this all unfolds - I will update!

You'd have been better off just buying the top half of the thermostat (the bit which breaks)

Skoda Fabia 1.4 Mpi Thermostat - £18.61 : Skoda Parts, Jorily, The Skoda Parts Shop - Probably the UKs largest independent skoda parts supplier

Cheaper than buying the full thing at £26-45.

Thanks Jorily. I have been advised by several sources that I should replace the whole unit. I was told by Skoda today that the whole thermostat is likely to have collapsed andthat I should replace the whole unit. Can you explain more about why I should just get this part? Skoda advised me against doing this!

Actually, the part that Graham's listed would probably have done you since the sensor is fairly new. I thought you just got the plunger, but the half of the housing that it's clipped into is the part that fails, so I reckon you'd have been OK with just that bit.

Having said this, it looks from your other posts as though your 'new' sensor may be faulty as well, in which case getting the whole lot with another sensor bundled in as you have done will at least eliminate that as a problem, although if a new thermostat AND sensor doesn't cure it, then I think you'd have to get a fault code scan and go from there...

HTH

Brilliant - thanks for the help. Getting the part today Ap0gee and giving it a go. I've just checked the sender connections and they seem sound. Sprayed a bit of WD40 on them and I'll give it a drive in a second and see how it goes.

Quick question about the process of changing the part over: I noticed that there seem to be metal bands holding the pipes on to the plastic body. Do I just use a pair of pliers to bend these off with? And how do I then go about bending them back on so they are tight?

CHeers for the all the effort

They're spring clips, so what you do is put the two prongs in the jaws of your pliers / grips and squeeze the together which opens out the clips so you can slide them off. This is why grips are better, as you can lock them off while you slide the clips off, rather than having to keep squeezing pliers. If you do that, you should be able to re-use them, but if all else fails, you can replace them with Jubilee clips, if Haynes is anything to go by!

Cheezmonkhai made a fair point about checking whether the radiator gets warm on a run. The 'stat failing CLOSED would cause this, although the sensor would have to fail as well to present symptoms like yours. Nevertheless, a stuck 'stat can cause MAJOR problems if not fixed, so it's another possibility you can rule out by swapping the whole lot.

excellent, thanks! Got the part - will have a bash tonight

Cheezmonkhai made a fair point about checking whether the radiator gets warm on a run. The 'stat failing CLOSED would cause this

The other way around, actually. If the thermostat is stuck closed, no coolant is getting to the rad, so the engine gets mighty warm and the rad stays cold. If the stat is stuck open, the engine will not warm up properly unless it's thrashed hard for a long time — the rad will likely be luke warm after a run.

Does anyone remember radiator blinds? The '59 Felicia had one, operated by a lever under the dash. Oooh, my lumbago...